Hydrologic Buffering and Earthquake Depth Distributions: A Falsifiable Framework for Groundwater–Tectonic Coupling

This preprint presents the Hydrologic Buffering Hypothesis, a falsifiable framework proposing that groundwater recovery and associated reductions in subsidence may influence the observable expression of tectonic strain through changes in earthquake depth distributions. Using M2.5+ earthquake catalogs from the Coachella Valley, Las Vegas Basin, and Southern San Joaquin Valley, the study evaluates shifts in median earthquake depth and shallow seismic expression across hydrologic phases. Monte Carlo randomization analyses provide statistical support for the strongest observational signals in the Coachella Valley. The manuscript introduces the Hydrologic Buffering Verification Index (HBI) and Seismic-Only Index (HBI*) to facilitate future testing and replication across independent groundwater basins. The framework is intentionally falsifiable and does not assert causation, earthquake prevention, or control of fault rupture timing.